Yale 135-16 – Engine Control Module (ECM) or Vehicle System Manager (VSM): Fuel Air Pressure minus (MAP) OORH (GM LPG Only) / Fuel Absolute Pressure Minus (MAP) Too High

The voltage signal from the MAP sensor (or fuel pressure sensor) is exceeding the maximum expected threshold, meaning the system is reading an abnormally high pressure value (or low vacuum) in the intake manifold.

• Yale and Hyster Forklifts
• Yale and Hyster forklifts (2005 and newer) with GM LPG engines
• Yale VX Series (e.g., GLC050VX)
• Hyster FT Series (e.g., H90FT, S50FT)

1. 1

   Inspect the wiring harness at the MAP sensor plug for broken wires, a short to the battery, or an open ground circuit

2. 2

   Inspect the vacuum hose running from the intake manifold to the MAP sensor to ensure it is not disconnected, cracked, or plugged

3. 3

   Check for mechanical engine issues such as a dead cylinder or a bad misfire (e.g., bad spark, loss of compression, or faulty injector) which can severely drop intake vacuum

1. 1

   Turn off the forklift and disconnect the battery negative cable.

   Ensure the machine is powered down before beginning the replacement.

2. 2

   Locate the MAP sensor.

   On these GM engines, it is typically mounted on a bracket located on top of the valve cover or near the intake manifold.

3. 3

   Carefully disconnect the vacuum hose from the MAP sensor.

   Ensure the hose is not damaged during removal.

4. 4

   Depress the lock tab and disconnect the electrical connector at the MAP sensor.

   Disconnect the wiring harness from the sensor.

5. 5

   Unbolt or unclip the MAP sensor from its mounting bracket.

   Remove the faulty sensor from the engine.

6. 6

   Install the new MAP sensor into the bracket.

   Secure the new sensor in place.

7. 7

   Reconnect the electrical connector and ensure the lock tab clicks into place.

   Verify a secure electrical connection.

8. 8

   Reconnect the vacuum hose securely to the sensor nipple.

   Ensure there are no vacuum leaks at the connection point.

9. 9

   Reconnect the battery negative cable, turn the key on, and clear the fault codes from the dash/display.

   Test the throttle response to ensure the code does not return.